Not easy topic - not easy. Why? Because the impostor syndrome is a tricky thing. Without diving deep in what is the impostor syndrome here is a digest about it:

When a person feels that he don't deserve successes or think he is not smart/gifted/talented, when somebody doubts about his skills and think he is a fraud than this person suffers with impostor syndrome. (It is not a official definition, just my summarize)

If you want to read more here is the Wikipedia article.

Okay, what is the base situation?

To be honest, programming is a ridiculously hard job. Not that way like mining the bauxite but it's not easy and it demands a lot of skill and knowledge to achieve acceptable results. So, it should be enough to not think about our-self as a cheater, however the situation is more subtle.

Imagine that you are a new employee in a company. A ton of new thing - new co-workers, new rules, new community habits just the sucks with the printer is familiar (Thanks' God...at least something). And of course we are facing with a completely new software product, new code base and doesn't matter you are junior, medior, senior or a geek-Gandalf, to learn a new code base is not just a hard, it is also exhausting. Furthermore, everybody around you knows more about the code then you. It's evident - they have been working with this code for years but I know this fact doesn't help a lot. But why?

The maze of our ego

Keep in mind - everybody wants to be better than actually he is and for this reason they show a face to the world what they would like to have. I believe it's okay if they don't create a toxic environment with this act but in my view to accept our current state of development is by far better approach. I know - easier to say.....

This all thing is about us and the world and the one is more complicated than the another.

Epictetus is on the agile ceremonies

There lived a slave in Roman Empire - named Epictetus. He had a really interesting life and I don't want to tell too much about him therefore here is another link to Wikipedia.

Epictetus's philosophy arranges the things in two set - things what we can effect them and things what we can't. In my opinion, this is a great model to catch essential of the issues because we just have to separate the things and after we have to do only our part and we have no more job. Additionally, if we concentrate more and more on our things what we can change (our thoughts, emotions, taking responsibilities) , set of things what we can change will be increase.

But how looks like it in practice?

So, the person thinks he is a fraud because no enough skills and such things. If person realize this is (probably) only in his head, he'll be able to change it. Everybody goes through a interview process where interviewers decided that the candidate is good enough to join to the company. Please, let's focus on our-self. If they have something point, they'll say it and they won't think you are cheater of the programmers society and you aren't member of the tribe. In my experience, the more experienced devs are humble enough to help you because they remember their-self when they were less experienced.

Until they don't give you any feedback, you can concentrate on the things what you can effect. For instance, sharpening your skills, studying the code base and don't forget....you can take questions. It's important but we can forget this. You aren't impostor just you are there where you are in your developer journey and it is fine. Please, don't shame your skills because you can grow and keep in mind: you are perfect - not flawless.